This invention relates to devices for mounting at least one object within a hole in a panel. such as devices used for mounting a recessed lighting fixture within a ceiling panel having an exposed surface and an opposed hidden surface, specifically to an apparatus comprising a housing having an opening in one end; a flange attached to the housing around its opening for engaging the exposed surface of the panel around the hole; and a plurality of self-recoiling flat springs each having an infinite number of uncoiled extended states when subject to tensioning forces for engaging the hidden surface of the panel and biasing the flange against the exposed surface of the panel so that the flange and the self-recoiling flat springs in combination provide secure rapid vibration-resistant positioning of the housing within the panel hole. Removal of the housing from the panel is also rapid and simply requires the application of a tensioning force to the flange to pull it away from the exposed surface of the panel until the self-recoiling flat springs extend sufficiently to release the housing from the panel hole. A theft-resistant embodiment of the present invention comprises apertures in the flange and a removal and installation tool which when inserted through the apertures promptly unrolls the self-recoiling flat springs into their uncoiled extended state for easy movement thereof through a panel hole at the same time the housing is drawn away from the panel hole. During installation, when the flange of the theft-resistant embodiment becomes positioned against the exposed surface of the panel, the tool is withdrawn and the self-recoiling flat springs instantaneously recoil to engage the hidden surface of the panel and become biased against it to lock the housing securely in place within the panel hole. The tool may later be inserted through the apertures in the flange to unroll the self-recoiling flat springs into their uncoiled extended state and assist the rapid removal of the housing from the panel hole. The present invention is vibration-resistant when installed into a panel hole, can be used with panels of any thickness dimension, can be inserted into panel holes which are not accurately cut, and the theft-resistant embodiment comprises a slight inward fold on the unattached inwardly coiled end of each self-recoiling flat spring for slip-proof engagement with a rectangular cutout in the distal end of the insertion and removal tool as well as engagement with the hidden surface of the panel to prevent housing removal without the tool. Slip-proof engagement results from the self-recoiling flat springs being positioned so that they tend to re-roll away from the housing. This positioning also results in the folds being biased toward the arms of the tool when engaged thereby so the housing and tool together can be rapidly withdrawn from a panel hole. Applications of the present invention may include, but are not limited to, use in the rapid mounting of lighting fixtures into ceiling panels during construction and renovation work, the rapid mounting of industrial gauges, releasable vibration-resistant mounting of gauges in motorized racing and test vehicles, and the mounting of any other object into a panel for which rapid installation and removal would be beneficial for time-saving repositioning and reuse of the object in other locations.